Dutch medieval book historian Erik Kwakkel stumbled upon a gorgeously illustrated 1692 tome devoted to the art of mixing watercolors author identified as A. Boogert is a nuanced guide to mixing watercolor paints

"You are looking at medieval parchment - animal skin - that was stabbed, cut and stitched up.While some cuts were simply stitched up with a thin parchment cord, it also happened that book producers turned these defects into art.